Intermittent scan chain fault diagnosis based on signal probability analysis

A new algorithm to diagnose intermittent scan chain fault in scan-based designs is proposed in this paper. An intermittent scan chain fault sometimes is triggered and sometimes is not triggered during scan chain shifting, which makes it very difficult to locate the fault sites. In this paper, we provide answers to three questions: (1) Why intermittent scan chain faults happen? (2) Why diagnosis of this type of faults is necessary? (3) How to diagnose this type of faults? The experimental results presented demonstrate that the proposed diagnosis algorithm is effective for large industrial designs with multiple intermittent scan chain faults.